Apparatus for elevating granular material



Jan. 13, 1953 R. KOLLGAARD APPARATUS FOR ELEVATING GRANULAR MATERIALFiled Jan. 17; 1951 INVENTOR erjYollgaard Keyn BY \ALMW M2 MA.

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d 3 a +1 4 I .7, i 2 a I q, w z llvl 4 w A m ATTORNEY Patented Jan. 13,1953 APPARATUS FOR ELEVATING GRANULAR MATERIAL Reyner Kollgaard, Media,Pa., assignor to Houdry Process Corporation, Wilmington, DeL, acorporation of Delaware Application January 17, 1951, Serial No. 20 ,323

' 5 Claims. (01. 302-17) This invention relates to improvements in asystem for elevating granular material. The invention is particularlyapplicable to petroleum refining and other chemical processing systemsinvolving the transfer and circulation of contact material, such ascatalyst, of discrete particle S 29.

'In connection with such systems, catalyst or other contact material inthe form of granules, pellets, beads, etc, of comparatively largeparticle size, is continuously circulated through one or more reactionzones in a path having a downflow portion along which the granularmaterial is passed by gravity flow, and an upflow portion along whichthe granular material is elevated from a lower level to a substantiallyhigher level. In earlier systems requiring the elevation of suchgranular material, mechanical means, such as bucket elevators, werecommonly employed for transporting the material to the requiredelevation for recirculating the material through its downnow path. Morerecently, however, such elevation of granular material has been effectedby pneumatic means, employing for this purpose an elongated verticallift pipe associated with an introduction chamber at its lower end,wherein granular material, such as catalyst, is engaged by a gaseouslift medium supplied in sufiicient quantity to convey the catalystupwardly through the lift pipe, and a disengaging chamber at its upperend wherein the catalyst may be disengaged from the lift gas andreturned to the downflow path. Pneumatic lift systems employing both asingle lift pipe and multiple lift pipes are in commercial use. Themultiple lift systems may comprise a series of individual lift pipesextending from the lower lift hopper or introduction chamber to theupper lift hopper or disengaging chamber, or they may comprise shortmultiple lift feeder pipes which extend from the introduction chamberupwardly into the lower end of a large single lift pipe.

The principal application of the present invention is in connection withthe multiple lift sys tems comprising either multiple lift pipes ormultiple lift feeder pipes discharging into a single lift pipe.

A typical hydrocarbon conversion system to which the present inventionmay be applied is that illustrated and described in an article entitledHoudriflow: New Design in Catalytic *Cracking, appearing on page '78 ofthe January .13, 1949, issue ofthefOil and Gas Journal.

A problem of primary importance, in the elevation of granular solids ofa frangible nature, is

that of attrition as a result of impact and friction, and various meanshave heretofore been employed for the purpose of maintaining attritionlosses at a minimum.

It has been demonstrated that granular solids may be smoothly introducedinto lift pipes of comparatively small diameter, and may be efficientlytransported through such small diameter pipes with desired low attritionlosses when the granular solids are introduced into the lift pipe insuch manner as to maintain suitable concentration of the movingparticles in the lift pipe and linear velocities therein at which suchparticles will move upwardly in substantially straight-line flow. As thediameter of the lift pipe is extended to greater and greater size forthe purpose of handling the required large quantitles of granular solid,the attainment of straight-line flow at the inlet to the lift and withinthe lower portion thereof becomes more difficult, because of thetendency of the particles to flow laterally in a random motion withresultant introduction of factors tending to cause attrition.

It has also been demonstrated that improved lifting of granular solidmaterials, free of the above-mentioned difficulties, can be achievedeven in lift pipes of comparatively large diameter if such granularmaterial is initially accelerated upwardly through one or morecomparatively narrow feeder pipes discharging at their upper ends intothe lower end of the main lift pipe. Such method of operation tends tominimize or to eliminate the possibility of deviation of the granularmaterial from straight-line flow.

Whether a single lift pipe, having a plurality of feeder pipes at thelower end, or multiple separate lift pipes are employed, it is difficultto obtain desirable characteristics of flow throughout the lift pathwithout maintaining uniform conditionsat the inlet ends of themultipleilift pipes or the multiple feeder pipes. Variations in pressureat one or more inlets to the lift as a result of erratic operationthereof, may cause preferen tial flow of lift gas to other inlets atwhich a lower pressure exists, thereby causing erratic operation of thelift.

It has been observed that when granularmaterial is pneumaticallyelevated through a plurality of closely-spaced parallel confined liftpaths by initially starting a flow of lift gas alone along the lower'-'portions of the confined lift paths, and then, ;at a higher leveltherein, lintroducing granular material laterally therein from a commonbed surrounding the lift pipes, any substantial variation in pressure atthe granular material inlets of one lift path as a result of erraticlift performance therein will be reflected in the op eration of thenearest adjacent lift paths. The reason for this is that there is apreferential flow of lift gas from the former to the latter by reason ofthe fact that the narrow moving mass of granular material does notprovide sufficient resistance to a flow of gas from the inlet of higherpressure to adjacent inlets of lower pressure,

In accordance with the present invention, the possibility ofpreferential flow of lift gas from the solids inlet of one lift pipe ofa multiple lift unit for granular catalyst, or other contact material,to the solids inlet of another lift pipe receiving catalyst from acommon bed is significantly decreased by segregating the solids inletswithin the catalyst bed without increasing the lateral spacing of thelift pipes. The extent of segregation is such that the path for gasmigration through the catalyst bed from one solids inlet to a solidsinlet of the nearest adjacent lift pipe offers so high a resistance toflow that under the pressure differential existing at the time oferratic I bed contained within the lower lift hopper. The

annular Well surrounding each lift pipe inlet terminates adjacent butbelow the lower ends of the catalyst inlet ports in the side of the liftpipes. The depth of the well is such as to contain a sufficient columnof catalyst to cause a resistance to flow of lift gas upwardly throughone column, laterally to the adjacent column, and downwardly through thelatter. The resistance to flow through the above-described path is suchthat most gas will flow up the erratically operating lift pipe ratherthan to the adjacent lift pipes.

For a fuller understanding of the invention and the advantages thereof,reference may be had to the following description read in connectionwith the accompanying drawing forming a part of this application, which:

Fig. 1 is a schematic view in elevation showing the general arrangementof the processing vessels, pneumatic lift, and transfer lines of atypical hydrocarbon conversion system; 7

Fig. 2 is an enlarged longitudinal cross-sectional view of the lowerlift hopper of Fig, 1; and

Fig. 3 is a modification of the lower lift hopper of Fig. 1 showing itsapplication to a multiple lift system employin a plurality of separatelift pipes for conveying catalyst to the desired point of elevation.

Referring to Figure l of the drawin catalyst in the form of granules,pellets, beads, etc is supplied to the downfiow path of the hydrocarbonprocessing system from a lift hopper l I, to which the catalyst haspreviously been elevated by means of a pneumatic lift. Lift hopper llincludes a disengaging zone or chamber wherein the catalyst is separatedfrom the lift gas, the latter being removed through gas outlet line {2.and the catalyst (-3 being continuously withdrawn from the lower endofthe lifthopper. through aseal leg it and introduced into the upper endQf-a processing vessel l5 comprising an upper reactor section (5 and alower regenerator section I! of greater diameter than the reactorsection.

Liquid hydrocarbon feed is supplied to the reactor section l6 of vessel[5 through inlet line 18. As will be understood to those familiar withthe art, hydrocarbon vapors may accompany the liquid hydrocarbons aspart of the charge. Section It includes a reaction chamber wherein thehydrocarbons are contacted with the catalyst introduced through seal leg[4 to carry out the desired hydrocarbon conversion. Process steam may beintroduced into the reaction chamber through inlet line [9, and steam orany other suitable inert gas may be introduced at the upper end ofvessel [5 through inlet line 20 for the purpose of providing a gas sealin the seal leg M. The catalyst, which has become spent by reason of acarbonaceous deposit formed thereon during the reaction, together withthe gaseous products of reaction, pass downwardly by gravity flow fromthe reaction zone at the lower end of section 16 into a solids-vapordisengager section located at the upper end of the enlarged regeneratorsection if, wherein the gaseous reaction products are separated from thespent catalyst. The gaseous reaction products are withdrawn from thevessel :5 through vapor outlets 2 I. The separated spent catalystgravitates downwardly through a purging section wherein it is contactedwith a stripping gas, such as steam, introduced through inlet 22. Thepurge steam and the vaporizable material removed from the spent catalysttogether with the separated gaseous material, pass out of the vessel I5through the vapor outlets 2!. From the purging section, the spentcatalyst gravitates through a suitable internal conduit arrangement intothe regenerating zone of regenerator section H. Within the regeneratingzone, the spent catalyst is subjected, in known manner, to successivestages of regeneration. In the upper stage, oxygen-containing gasintroduced through inlet 23 passes countercurrently to the flow ofcatalyst. The gaseous products formed in the upper stage of regenerationare removed from vessel l5 through flue gas outlet 24. From the firststage of regeneration the catalyst gravitates downwardly to the secondstage of regeneration, intermediate cooling by indirect heat exchangewith a circulating medium being provided, if desired. Oxygen-containinggas is supplied to the lower stage of regeneration through inlet 25, andthe gaseous products of regeneration are removed from the upper end ofthe second regenerating stage through flue gas outlet 26.

At the lower end of vessel l5 the regenerated catalyst is withdrawnthrough seal leg 2'! and introduced into the upper end of lower lifthopper 28. A lift pipe 29 extends between the upper and lower lifthoppers, providing a passageway for the upward conveyance of catalysttherebetween. Lift gas introduced into lower lift hopper 28, as throughinlet lines 30 and 31, engages the regenerated catalyst and conveys itinto and upwardly throughthe lift pipe 29 to the upper lift hopper I I.A more detailed description and illustration of the processing portionof the hydrocareon conversion system is not given for the reason thatthe invention is directed primarily to improvements in the pneumaticlift, and particularly to the inlet end thereof.

3 A clearer illustration of the meansfor effecting engagement betweenthelift gas and the catalyst and the upward'convey' e th reo t r u h thelift ipe maybe had by reference to Figure d,

which shows an enlarged cross-sectional elevation view of the lower lifthopper 28, the lower end portion of the lift pipe- 29, and the multiplefeeder conduits, presently to be described, for introducing the catalystinto the lift pipe.

Referring to Figure 2, the lower end of the lift pipe 29 is attached, asby a flanged connection, to the upper end of a housing member whichforms the lower lift hopper 28. A tube-sheet 32 extends across the upperend of the hopper 28, preferably secured between the connected ends ofthe lift pipe and the hopper. Tube-sheet 32 supports the upper ends of aseries of relatively short feeder conduits 33 having a combinedcross-sectional flow area as near to the cross-sectional flow area ofthe lift pipe 29 as is practicable. Any suitable number of feederconduits, may be employed, and they are preferably arranged in a uniformdistribution pattern across the area of the tube-sheet 32. A horizontalpartition 34 extends across the lower region of the hopper 28, and isprovided with a series of openings corresponding to and concentric withthe feeder conduits 33. The openings are of substantially greaterdiameter than the diameter of the feeder conduits and are provided withcylindrical members 35 attached along their upper edges to the perimeterof the openings in partition 34. End plates 36 extend horizontally fromthe lower perimeter of cylindrical members 35 to the outer surface ofthe feeder conduits 33, thus closing the lower end of the annular spacebetween the cylindrical members 35 and the feeder conduits 33 andforming individual annular wells 31 about each of the feeder conduits.The lower ends of the feeder conduits extend a substantial distancebelow the bottom of the wells 31 and are in open communication with thechamber 38 formed in the lower region of the lower lift hopper 28 belowpartition 34. Orifice plates 39 are set in each of the feeder conduits33 adjacent the lower end. A circumferential row of ports 40 areprovided in the side wall of each of the feeder conduits 33 at a levelslightly above the end plates 36 to provide open communication betweenthe wells 31 and th feeder conduits 33.

The catalyst introduced. into the upper end of lower lift hopper 28,through seal leg 21, forms therein a downwardly moving compactnon-turbulent bed 4!, supported by the partition 34 and completelyfilling the wells 31. The downwardly moving catalyst passes into thewells 31 and thence into the feeder conduits 33 through the side ports49, the latter preferably comprising an equi-spaced circumferential rowof longitudinally extending slots. To facilitate the movement ofcatalyst downwardly in bed 4! and laterally through the slots 49 intothe feeder conduits 33, a quantity of lift gas is introduced throughinlet line 3| into the free space formed beneath the annular member 42attached along the inner wall of housing 28. Such gas passes with thecatalyst into the feeder conduits and thence into the main lift pipe tosupplement the primary supply of lift gas and to serve as control gasfor varying the rate of catalyst flow through the lift.

The primary stream of lift gas is introduced into the chamber 38 at thebottom of lower lift hopper 28 through inlet line 30. Chamber 38 servesas a manifold for supplying the primary stream of lift gas to the lowerend of each of the feeder conduits 33. The orifice plates 39 serve tomaintain a constant and uniform feed of lift gas into each of the feederconduits. The lift gas introduced through inlet line 30 constitutes themajor 6 portion of the lift gas necessary to elevate the catalystthrough the feeder conduits into the main lift pipe 29. I

By reason of the increased cross-sectional flow area of the main liftpipe 29, as compared to the combined flow areas of all of the feederconduits 33, there is a substantial reduction in gas velocity, andincidentally in the acceleration .Iof the catalyst conveyed by the gasupon discharge into the main lift pipe 29. In order to obviate suchvelocity reduction and to maintain a more nearly uniform movement ofcatalyst into and upwardly through the lift pipe, additional lift gas issupplied through inlet line 43 to the lower region of the lift pipe,preferably below the'discharge level of the feeder conduits 33. Theliftgas introduced through inlet line 43 is supplied in sufficient quantityto atleast maintain the discharge velocity of the catalyst'as it passesfrom the feeder conduits 33 into the lift pipe 29. If desired, suchadditional lift gas may be supplied in sufficient quantity to provide asubstantial acceleration of the catalyst after it discharges into thelift pipe.

Fig. 3 illustrates the applicability of the invention to a multiple liftcomprising a plurality of separate lift pipes 29 extending upwardly fromthe lower lift hopper 28. Although not illustrated in the drawing, it isto be understood that all of the lift pipes 29 extending into the upperlift hopper II for disengagement of the catalyst and the lift gas.

The lower ends of lift pipes 23 pass through tube-sheet 32, catalyst bed4!, and cylindrical well-forming members 35, similar to the feederconduits 33 of Fig. 2. The lift pipes 29 are slotted in the same manneras feeder conduits 33, so that catalyst descending into the wells 31 mayenter the lift pipes 29' through the slots 40'.

Obviously any modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposed asare indicated in the appended claims.

I claim as my invention:

1. Apparatus for elevating granular material by means of a gaseous liftmedium comprising a plurality of closely-spaced parallel lift pipes, ahousing surrounding the lower portion of said lift pipes, said housinghaving a lower chamber in open communication with the lower ends of saidlift pipes and an upper chamber adapted to contain a downwardly movingbed of said granular material surrounding said lift pipes, means in thelower region of said upper chamber forming individual elongated wellsabout said lift pipes adapted to receive granular material from saidbed, said lift pipes having openings into the lower region of saidwells, means for introducing lift gas into said upper chamber, and meansfor introducing lift gas into said lower chamber, whereby the latterlift gas passes upwardly into the lower ends of said lift pipes andengages at a higher level therein said granular material conveyedthrough said openings by said firstmentioned lift gas, and the combinedstreams of lift gas convey said granular material upwardly through saidlift pipes.

2. Apparatus as defined in claim 1 including a single lift pipeencircling at its lower end the upper ends of said plurality of liftpipes and to receive the streams of granular material and lift gasdischarged therefrom, and means for introducing lift gas into the lowerregion of said single 7 lift pipe below the level of discharge from saidplurality of lift pipes.

3. Apparatus for elevating granular material by means of a gaseous liftmedium comprising a plurality of closely-spaced parallel lift pipes,means for introducing a gaseous lift medium from a common source intothe lower ends of said lift pipes, a chamber adapted to maintain acompact moving bed of said granular material above the lower ends ofsaid lift pipes, means for passing said granular material in separateconfined streams from said chamber into said lift pipes, said streams ofgranular material being introduced laterally into said lift pipes at alevel spaced a substantial distance above their lower ends, and meansfor introducing a gaseous liit medium into said compact moving bed ofgranular material for conveyance with said separate confined streams ofgranular material into said lift pipes.

4. Apparatus as defined in claim 3 wherein said confined streams ofgranular material are of such length as to impose a substantialrestriction to gas flow along the path extending from the granularmaterial inlet of one lift pipe, oountercurrently through its confinedfeed stream of granular material to said moving bed, laterally through aportion of said bed to an adjacent confined feed stream, andconcurrently through the latter to its associated lift pipe inlet.

5. Apparatus as defined in claim 3 including a relatively large-sizelift pipe having its lower end encompassing the upper end portions ofsaid plurality of lift pipes and forming a vertical extension thereof,closure means sealing the spaces between the lower end of saidlarge-size lift pipe and said plurality of lift pipes, and means forintroducing a gaseous lift medium into the lower end of said large-sizelift pipe at a level substantially below the discharge level of saidplurality of lift pipes.

REYNER KOLLGAARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 299,279 Sachs May 27, 18841,730,195 Davis OCt. l, 1929

